Messed up my C2 again, Driveability)
Thread Starter
Drifting
Joined: Feb 2010
Posts: 1,734
Likes: 267
From: Richmond Texas
Messed up my C2 again, Driveability)
Screwed up my car again.
Parked the car and somehow left the key on. Went back a couple of days later..Battery completely dead, put a fresh battery in the car, fires right up, Idles really well but bucks on take off, almost like the accelerator squirter isn't working (it is) runs rough going down the road. Figured I toasted the points leaving the key on so I got a new set of points and condenser , all they had was a uni set (AC Delco D1007), set the dwell to 30*, set the timing to 12 initial, 32 total, hooked up the vacuum advance,( it works, hooked to manifold vacuum port on carb), Car still bucks on take off and runs bad going down the road, tried a used coil off my Plymouth, didn't help. Voltage at coil with engine running is 10.5.
I am at a loss, what else could I have messed up? Anyway I could have messed up the cap or rotor leaving the key on?
Parked the car and somehow left the key on. Went back a couple of days later..Battery completely dead, put a fresh battery in the car, fires right up, Idles really well but bucks on take off, almost like the accelerator squirter isn't working (it is) runs rough going down the road. Figured I toasted the points leaving the key on so I got a new set of points and condenser , all they had was a uni set (AC Delco D1007), set the dwell to 30*, set the timing to 12 initial, 32 total, hooked up the vacuum advance,( it works, hooked to manifold vacuum port on carb), Car still bucks on take off and runs bad going down the road, tried a used coil off my Plymouth, didn't help. Voltage at coil with engine running is 10.5.
I am at a loss, what else could I have messed up? Anyway I could have messed up the cap or rotor leaving the key on?
Instructor
Joined: Dec 2025
Posts: 228
Likes: 77
From: Pachuta, MS
This is a tough one but I can't see anything like this damaging the cap or rotor. What I can see is something like ignition switch contacts being overheated (though not likely) or the resistor being overheated or possibly the voltage regulator barely working now or the coil wire getting so hot (from the coil) that it barely conducts spark now because the carbon conductors have broken down or a poor connection between the switch and the coil. I suggest that you eliminate all the primary ignition causes at one whack (since you have replaced the points and condenser) by jumpering from +12v to the '+' terminal of the coil. If the problem persists, I would then rig a temporary wire from the points to the '-' terminal of the coil. You could probably run it through the window in the cap. If that fails then replace the coil wire or at least test it with an ohmmeter. That ought to be a good start. Final thought: Does this thing have an electric choke? You could have burned him up. If there is a radio suppression capacitor connected to the '+' side of the coil, you might try disconnecting him(just the lead) because he could have been damaged by the coil's heat.
Last edited by acstephenson; May 9, 2026 at 06:34 PM.
Le Mans Master
Joined: Aug 2005
Posts: 6,529
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From: Temple Terrace Florida
You can for testing purposes, connect a wire from the positive side of the coil to the positive side of the battery, That will bypass the ignition switch and give full battery power to the ignition system. Jerry
Thread Starter
Drifting
Joined: Feb 2010
Posts: 1,734
Likes: 267
From: Richmond Texas
It has 10.5 volts running to the + side of the coil. I can hot hire it and see if that helps but I thought it was supposed to have around 6 volts running
Instructor
Joined: Dec 2025
Posts: 228
Likes: 77
From: Pachuta, MS
Somewhere between 7 & ~ 9 is typical but it varies. The important point is that it has nearly 12 VDC while cranking. The only reason that 12 volts isn't supplied all the time is that it will burn the points fairly quickly but for testing purposes that's fine. Your 10.5 volts is a bit high and suggests that the coil isn't pulling quite enough current. Get the jumper test out of the way and go from there. One thing that could cause the somewhat abnormal voltage is a broken wire between the distributor ground and the breaker plate. It might have burned up.
Thread Starter
Drifting
Joined: Feb 2010
Posts: 1,734
Likes: 267
From: Richmond Texas
Somewhere between 7 & ~ 9 is typical but it varies. The important point is that it has nearly 12 VDC while cranking. The only reason that 12 volts isn't supplied all the time is that it will burn the points fairly quickly but for testing purposes that's fine. Your 10.5 volts is a bit high and suggests that the coil isn't pulling quite enough current. Get the jumper test out of the way and go from there. One thing that could cause the somewhat abnormal voltage is a broken wire between the distributor ground and the breaker plate. It might have burned up.
One thing I did notice is that when I hooked the positive side of the coil wire to the coil it arcs pretty good. Never noticed that before. Is that normal? That was with the points closed, when they are open, it doesn't do that. I attached the video hopefully
Last edited by SledgeHammer 2.0; May 10, 2026 at 06:43 PM. Reason: Grammer, added content
Drifting
Joined: Sep 2024
Posts: 1,588
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From: Florida
Years ago a mechanic at the shop struggled with the same symptons as you are.. It turned out to be a bad condenser. I read where you put in a set of unipoints and I have no idea how to " check " a condenser but thought I would toss it in the ring here...
Instructor
Joined: Dec 2025
Posts: 228
Likes: 77
From: Pachuta, MS
That spark looks a little strong indicating the coil may be pulling too much current. Are you sure that Plymouth used coil is good? (It could also have introduced some fatal virus that GM cars have no antibodies for.) Something I do note in your image are what appear to be little bubbles in the coil wire insulation. I would be really interested in knowing the resistance of your coil wire; it might have been cooked by the coil's heat, This whole time I've had the feeling that we've been drawn down the ignition path but that it may be something else such as electric choke, electric fuel pump, or some other component that was damaged. At least you have eliminated a bunch of things that it ain't like bulkhead connectors, resistors, points and condenser. This thing still is screaming bad coil because these are the classic symptoms but it could be the coil wire.
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Thread Starter
Drifting
Joined: Feb 2010
Posts: 1,734
Likes: 267
From: Richmond Texas
That spark looks a little strong indicating the coil may be pulling too much current. Are you sure that Plymouth used coil is good? (It could also have introduced some fatal virus that GM cars have no antibodies for.) Something I do note in your image are what appear to be little bubbles in the coil wire insulation. I would be really interested in knowing the resistance of your coil wire; it might have been cooked by the coil's heat, This whole time I've had the feeling that we've been drawn down the ignition path but that it may be something else such as electric choke, electric fuel pump, or some other component that was damaged. At least you have eliminated a bunch of things that it ain't like bulkhead connectors, resistors, points and condenser. This thing still is screaming bad coil because these are the classic symptoms but it could be the coil wire.
A couple of years ago my bulkhead connector fried out and I put an engine and under dash wiring harness in it, so I think the wiring is good. I haven't replaced the tail light wiring harness. I don't have an electric choke nor a electric fuel pump. I will measure the resistance and get back, This car is wearing me out. I have owned it since 1988 and it's been a great car up till 4-5 years ago.
Drifting
Joined: Apr 2011
Posts: 1,605
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From: Australia
I don’t think it’s the root of the problem, but can’t be helping.
Last edited by anyChevy; May 10, 2026 at 10:13 PM.
Instructor
Joined: Dec 2025
Posts: 228
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From: Pachuta, MS
I've had one other thought (and it fits with my psychic tingling that we've been looking at the wrong stuff): All of this could be nothing more than a poor/broken battery or ground connection around the battery itself --- especially the smaller cables. These batteries (especially the non-AC cars) can be a pain to get in and out and it would be very easy to damage or fail to tighten a cable in the process. Measuring voltage across the battery while it's running might also provide a clue.
Drifting
Joined: Dec 2014
Posts: 1,752
Likes: 137
From: Chantilly Virginia
I would look very closely at the path from the points to the coil. The breaker plate is moving frequently during startup and driving (especially if you are having misfires) If you tested with a jumper from the points to the coil, did you disconnect the existing coil wire at the points or just parallel it with the jumper?
Thread Starter
Drifting
Joined: Feb 2010
Posts: 1,734
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From: Richmond Texas
Okay following up. I tried everything, different coils, different wires, jumped the coil to 12v, ran a jumper from the points to the coil... everything I could think of. Bought another set of unipoints (off of amazon this time) and Tadaaa, it runs way better. Still has a little miss going down the road I need to figure out, but it looks like the first set of unipoints were defective. I am going to drive it some more to make sure it doesn't come back, but maybe the new set was just defective.
Thanks for all of y'alls help.
Thanks for all of y'alls help.
Instructor
Joined: Dec 2025
Posts: 228
Likes: 77
From: Pachuta, MS
I'm surprised that the dwell was able to set normally with a bad set of points/condenser without you noticing something was off. Anyway I'm glad you got him running but when you made the last change you might have accidently fixed him by jiggling the breaker plate ground lead. It's the wire that goes from one of the vacuum advance screws and connects to the movable breaker plate. I mentioned him earlier. Did you check that wire?
Drifting
Joined: Sep 2024
Posts: 1,588
Likes: 1,042
From: Florida
Okay following up. I tried everything, different coils, different wires, jumped the coil to 12v, ran a jumper from the points to the coil... everything I could think of. Bought another set of unipoints (off of amazon this time) and Tadaaa, it runs way better. Still has a little miss going down the road I need to figure out, but it looks like the first set of unipoints were defective. I am going to drive it some more to make sure it doesn't come back, but maybe the new set was just defective.
Thanks for all of y'alls help.
Thanks for all of y'alls help.
Thread Starter
Drifting
Joined: Feb 2010
Posts: 1,734
Likes: 267
From: Richmond Texas
I'm surprised that the dwell was able to set normally with a bad set of points/condenser without you noticing something was off. Anyway I'm glad you got him running but when you made the last change you might have accidently fixed him by jiggling the breaker plate ground lead. It's the wire that goes from one of the vacuum advance screws and connects to the movable breaker plate. I mentioned him earlier. Did you check that wire?
I am not trusting this miracle fix either. I guess I could have gotten a bad part.
also with the new set of points the voltage at the coil while it is running has dropped to 8.1 volts
Instructor
Joined: Dec 2025
Posts: 228
Likes: 77
From: Pachuta, MS
I recently changed the points on my '54 using NOS Delco-Remy points and condenser. The car was running perfectly before but now it wouldn't crank. I checked all the wiring and voltages and the points settings and made sure that there was no protective coating on the contacts but the thing wouldn't fire. I then made a single pass over the points with my burnishing blade and he started right up. I suppose 70 years of oxidation in the box can do that and you might have been dealing with something similar on your much younger car.
Race Director
Joined: May 2006
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yes that ground wire is there, it’s tight and measured no resistance to ground.
I am not trusting this miracle fix either. I guess I could have gotten a bad part.
also with the new set of points the voltage at the coil while it is running has dropped to 8.1 volts
I am not trusting this miracle fix either. I guess I could have gotten a bad part.
also with the new set of points the voltage at the coil while it is running has dropped to 8.1 volts